1. Field of the Invention
This invention relates to a supporting structure for a tool rest applied in a lathe.
2. Prior Art
A lathe in which capstan rests are movably arranged on a sliding bed has some disadvantages that if the capstan rests are made to be approchable to main shafts, the sliding bed should be laterally installed at the front of and just below the main shafts, and in this case, the cut chips are prevented by the sliding bed from being dropped to cause a poor rate of recovery of the cut chips and a special cover device is required such as a bellows in order to prevent the cut chips from being advanced into the fine finished corrugated sliding surfaces of the sliding bed and damaging the sliding surfaces. Further, the lathe in which a sliding bed is applied to cause the capstan rests to be movable has fundamentally a disadvantage that it has an expensive manufacturing cost for the sliding bed and its adjustment during its assembling operation is hard to perform and is of a trouble-some operation.
A lathe in which capstan rests are arranged at the extremity ends of the capstan shafts in parallel with the main shafts is already known and this type of lathe has the following disadvantages.
That is, the disadvantages found in this type of lathe are consisted in that a distance between the capstan shafts and the main shafts should be spaced apart substantially in respect to a driving system, and in order to cause a tool to be approached to the main shafts with the spaced-apart distance being accommodated, either a diameter of the capstan is made large or the capstan rests should be of a long leg type, and in the former case, though it has an advantage that number of tools capable of being installed is increased, the weight of capstan is increased more than a proportion of two times of the increased diameter and a capstan indexing speed is substantially decreased as an outer circumferential distance is increased or as a source of power for driving or rotating the capstan, one with a high horse power is needed and in turn in the latter case, a high bucking load is applied to the tool rest to cause an accident of damage to occur.